1. Field of the Invention
This invention relates to a radio-frequency communication control system and a radio-frequency communication control method for a radio communication device, such as a mobile phone, in which a single-chip radio-frequency control circuit unit (normally called a RF control circuit unit) executes the process of transmitting and receiving a radio-frequency signal, and a baseband circuit unit (also called the baseband element) constituting another chip executes various digital processes on the data contained in the radio-frequency signal sent out from the radio-frequency control circuit unit.
In particular, this invention relates to a technique in which, in order to effectively utilize a plurality of radio-frequency control elements (normally called the RF control elements) included in the radio-frequency control circuit unit, an arbitrary one radio-frequency control element selected by the user, etc. can be connected to the baseband circuit unit by a simple method.
2. Description of the Related Art
Generally, a radio communication device, such as a mobile phone of the W-CDMA (wideband code division multiple access) type, comprises a radio-frequency communication control system (hereinafter referred to as the RF communication control system), including a single-chip radio-frequency communication control unit (hereinafter referred to as the RF communication control unit) having mounted therein a single-chip radio-frequency control circuit unit used primarily for handling an analog radio signal, and a chip having mounted thereon a baseband circuit unit primarily for handling digital data converted into a low-frequency signal.
The term “W-CDMA” indicates one of multiple connection systems for radio communication in which a radio wave in the same frequency band wider than CDMA (for example, 800 MHz to 2 GHz) is shared efficiently by a plurality of users using a spectrum spreading technique similar to the one for CDMA.
In the RF communication control system used in the conventional radio communication device, an arbitrary one of RF control elements in the RF control circuit unit is connected to the baseband circuit unit using a one-to-one interface of the baseband circuit unit.
In this setting method, however, all the interfaces of the baseband circuit unit are required to be changed each time one RF control element is changed to another RF control element (hereinafter referred to as the second RF control element). This makes it unavoidable to change the firmware (or software) processing system such as DSP (digital signal processor) required to set the interface of the baseband circuit unit appropriately.
In the RF communication control system used with the conventional radio communication device, therefore, the problem occurs in that the increased cost and labor is required to change the firmware processing system of the baseband circuit unit when changing the RF control element connected to the baseband circuit unit. As a result, a plurality of RF control elements cannot be efficiently used as resources.
For reference, Japanese Unexamined Patent Publication (Kohyo) No. 2004-510377 (Patent Document 1) and Japanese Unexamined Patent Publication (Kokai) No. 6-43979 (Patent Document 2) related to conventional RF communication control systems are described below.
Patent Document 1 discloses a signal processing device in which a low-noise exponential amplifier in an RF control element performs the selective control operation in such a manner that the magnitude of the signal level of a tuned channel frequency is compared with a predetermined threshold and, in accordance with the result of this comparison, it is determined whether or not the AGC (automatic gain control) operation in the RF control element is performed. At the same time, it is determined whether or not the AGC operation is performed also for the neighboring frequencies. Patent Document 1, however, never refers to the operation of changing the RF control element connected to the baseband element.
Patent Document 2, on the other hand, discloses a portable electronic device in which even in the case in which the battery is changed during communication, the operation of the portable radio telephone is restored to the state immediately before the source voltage stops being supplied, based on the information stored in a nonvolatile memory. Also in Patent Document 2, as in Patent Document 1 described above, however, the operation of changing the RF control element connected to the baseband element is not described.
The systems disclosed in Patent Documents 1 and 2, therefore, both pose the same problem as the conventional RF communication control system when changing the RF control element connected to the baseband element.